Rolling mill



J. E. FRIES ROLLING MILL June 4, l1929.

Filed July 17, l19,26

Patented .rune a, i929.

` Jeans-mms rains, or amiamo 1a, Ariana.' .1

BOLLDIG L.

.application led July 17,

This invention relates yto improvements in rolling mills and aims to provide an improved method and apparatus whereby the energy expanded-to overcome back-lash between vthe different transmission elements in the mill is regenerated and turned back to the electrical distribution system of the plant in order to save the cost of the power' now wasted for that purpose. f

. rIhe invention will be understood from the following speciication when read in connection with the accompanying drawings in which- F ig. 1 is a diagrammaticview of tour interconnected mills of a rolling mill showing the L. same driven by an A. C. motor and arranged to regenerate the energy er power consumed in overcoming back-lash and feed it back to th'e A C. line which drives the motor Fig. 2 is a similar diagram 'illustrating an arrangement in which the regenerated cur-` rent is fed back into aD. C. distribution sys-V Referring first to the arrangement bf Fig. 1, 10 represents the A. C. mill bus which sppplies current to a motor 12 which is connected through gears 13 and 14 with a shatt`16 arranged todrive the several. mills 18 and 20 which are operatively connected b v' a suitable coupling 22. The shaft 16 also drives mills 24 and'26`whic'h are connected .by a suitable coupling 28,. vA gear is operatively connected with the transmission element-s of the mill 18, this gear meshing with pinionj32 car' ried on the shaft of an induction ygenerator 34 which is connected through the contactor 36A and line 38 with the`A. C. mill bus 10. The mill 26 is similarly connected and the gearing and generator are correspondingly numbered at the right side of the drawing.

Heretofore, it has been the common prac- .tice in rolling mill operating methods to use a mechanical brake or drag at the end of each rolling train so as to prevent back-lash between the various transmission elements in l .the mill. Such a mechanical brake naturally consumes considerable power and. hence,

, adds considerable to the cost of operating the mill. Furthermore, mechanical rakes ref quire water cooling which also adds to the operating costs. My invention does away with this loss because the generator which I provide'to prevent back-,lash is of such capacity that its rated full load torque corresponds to -A the torque obtained bythe mechanicalbrake heretofore used. .By connecting the generawith the speed-all' of which are 1926. serial Nb. 123,233.

tor terminals to the electrical` distribution system, the poweris turnedback into the system, hence, the opposing torque is obtained without. substantially any loss of power except an extremely small loss depending upon the eciency of the generator 34. The load on the generator 34: can be varied bymeans of a suitable controller and consequently any opposing tonque within the limit of the generating capacity can be obtained. `When the speed ofthe main 12 varies ,with load the output ot the regenerative generators 34 will lvary `and consequently the braking eortiw-'ill also vary. To

driving motor l hold the braking torque practicallyconstant anyone of the well known induction motor load regulators 40 can be well applied to regup bankgradua'lly introduced into the secondary circuit by means of contactors' qperated byv relays which again are actuated by the variations/inthe primary circuit. Or' the contactors may be operated from ldie change ofspeed of the generator shaft rather than from y' the change of current in the primary circuit byvarlous means, such as automatic selfcntalned pumps creating pressures varying to the art. The arrangement in Fig. 2 is quite similar to that above,y described and they correwell known sponding parts are similarly numbered. In-

stead ofv using A.A C. generators' in this al'- rangement, I utili which feed'the D. C. bus 43.1 In the D. C.

ze al). C. generators42 system, the current output of the generators is kept approximately constant land consequently the braking torque. approximately constant by 'decreasing the iield excitation as the speed increases. This again is done by various well known regulators 44 such as the Tirrell regulator or a Brown-Boveri consta-nt current regulator or simply -b v providing a resistance bank in series with the fiel inding which is` gradually introduced as the speed increases either by contactors in combination with relays, or vcontactors in combination with automatic pressure pump as mentionedunder the C. system.

From the foregoing it is clear that the 'power which is utilized to `overcome back lash or lost motion between the transmission elements o f the mill is utilized to regenerate power which was heretofore Wasted in roll- -ing milloperations.

Various modifications may be made from the invention as claimed.

I claim: u' 1. The combination with a rolling mill 'train and its driving means, of an electric generator operatively connected to the mill and arranged to exert a braking action thereon to prevent back-lash and to recover energy usually wasted in braking.

2. The combination with a. rolling mill Ltrain'and al motor for driving said mill of an electric generator arranged toeXert a braking action to prevent back-lash between the bly" 4those skilled in the art Without departing transmission `elements of the mill and to re-v generate that partof theenergy consumed by said motor usually wasted braking.

and devices driven thereby of an electric generator arranged to exert a braking action to counteract back-lash 1n said devlces and to continuously regenerate part of the energy consumed by said motorI in driving said de-Y vices. 1

Inl Witness whereof, I have hereunto signed my name. P

' J. ELIAS FRIES. 

